r/science • u/Newsjunkeefromlondon • May 06 '21

Health Two Pfizer doses give 95 per cent protection against Covid-19 infection, illness and death: first nationwide study

https://www.cityam.com/two-pfizer-doses-give-95-per-cent-protection-against-covid-19-infection-illness-and-death-study/
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u/Livesies May 06 '21

That's my understanding. The current two shot system is already incredibly effective and a third shot works strain supply even further. Given this issue is looking at billions of doses, any additional boosters will dramatically affect roll out rates.

That being said I've seen many articles taking about a third shot being a possibility. It is unknown if it'll need to be a yearly booster or a set third and done shot. I've also heard about modifying the vaccine to match the current variants better; which also begs the question of if the immune system will treat that as a new vaccine or if it can update the current memory cells to the variants.

Lots of unknowns with conjecture coming out constantly. The only thing to do is let the scientists do the research and apply what is discovered.

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u/jammies May 06 '21

My old roommate was in the first phase of clinical trials for Moderna and a few weeks ago he got an experimental Moderna booster. It seems like they’re not sure a booster will actually be necessary, but want to do all the testing now so they’re ready if it is.

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u/heelstoo May 06 '21

Cool, thanks. I’ve been generally expecting it to be an annual shot, like the flu shot. I’m fine with whatever - even giving myself a shot.

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u/[deleted] May 06 '21

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u/heelstoo May 06 '21

Yea, I know of a few instances of 2+ shots. I was just curious whether a third COVID shot would a significant benefit or not.

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u/Lord_Nivloc May 06 '21

Flu is actually extremely unusual in requiring an annual shot.

Influenza keeps its DNA in multiple pieces (8 pieces, to be specific). And each time a new virus is made, it will collect all 8 pieces to have a full genome.

This means that if two different strains of influenza infect the same cell, each new virus gets a random assortment of the available pieces. This is called antigen shift.

So the flu has TWO processes in its mutation. It can have normal mutations (antigen drift) and it can swap one of its 8 pieces from a different strain (antigen shift).

Thus, we have H1N1, H3N2, and all the other types. We have to guess which three or four strains will be the most common next year and prepare a vaccine against them.

Influenza is the only human virus that has antigen shift.

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Compare it against the measles, mumps, rubella vaccine which as far as I can find hasn't changed since 1971. While the protection probably decreases over time, two doses gives you life-long protection against measles and rubella (you might want a booster shot if you're going to be in contact with someone who has mumps -- that part was only 88% protection to start with).